Electric incandescent lamp



June 28, 1955 s, LAMB 2,712,089

ELECTRIC INCANDESCENT LAMP Filed Jan. 2, 1951 lnven kor: Fvedrick 5.Lamb,

by M6 His A t t'ovneg.

ELECTREC ENQANDESCENT LAMP Fredrick S. Lamb, Cleveland Heights, Ohio,assignor to General Electric Company, a corporation of New York; patentdedicated to the Public insofar as it relates to lamps and lamp parts tothe extent stated in document recorded in the U. S. Patent Oh'iee,January 4, 1%4, Libel U432, page 394 Application January 2, 1951, SerialNo. M33336 5 Claims. (Cl. 313-274) My invention relates to electricincandescent lamps l and similar devices, and more particularly to amount structure therefor. The invention is of particular utility inconnection with electric incandescent lamps of the double-ended tubulartype having a base at each end and a filament extending longitudinallyof the lam such as shown and. described in U. S. Patent 2,032,791,Carton, and 2,158,849, Blake, assigned to the assignee of the presentinvention.

Lamps of the above-mentioned double-ended tubular type are in generaluse at present and comprise a tubular glass envelope having metal endcaps or bases sealed to the opposite ends thereof and an elongated mountsupported within the envelope between the metal end caps. The mountcomprises an elongated filament extending longitudinally of the envelopeand supported at a plurality of spaced points along its length by anumber of anchor wires insulatively fastened, by means of glass beads,to an elongated stay member which is resiliently compressiblelongitudinally between and supported in place by the end caps of theenvelope. The stay member comprises a main or center section preferablyformed of a metal channel so as to possess adequate rigidity andprovided at its opposite ends with terminal wires or end conductorswhich are electrically connected to the ends of the filament and whichbear against the end caps to make electrical connection therewith.

Heretofore, the glass support beads for the filament anchor wires ofsuch lamp mounts have been attached or fastened in place on the metalchannel by means of a fused seal therebetween, the glass beads beingsecurely held in place by the bond between the glass and the metal ofwhich the channel is formed. Such a fused seal type of attachment of theglass beads to the metal channel therefore requires the use of asuitable metal for the channel which will readily wet and adhere to theglass of which the support beads are made. Up to the present the metalmost suitable and preferably employed for this purpose has been aspecial high-chrome iron alloy of the so-called stainless steel type.Such a material, however, is quite expensive, thus adding materially tothe cost of the finished lamp.

It is an object of my invention, therefore, to provide an electricincandescent lamp of the above-mentioned general type having a mountstructure of simple and relatively inexpensive construction and easy tofabricate.

Another object of my invention is to provide an electric incandescentlamp of the above-mentioned general type having a lamp mount in whichthe glass beads which support the filament anchor wires are fastened tothe stay member of the mount by means of a mechanical interlocktherebetween.

According to the invention, the elongated stay memher, which ispreferably in the form of a metal channel. is provided with a pluralityof spaced apertures or slots through which the glass support beads forthe anchor wires are forced, when heated to a plastic condition, tocause the soft glass to spread over and grip the opposite fnited StatesPatent i ice sides of the channel around the apertures, thereby keyingand locking the glass beads in place on the channel.

Further objects and advantages of my invention will appear from thefollowing description of a species thereof and from the accompanyingdrawing.

in. the drawing, Fig. l is a longitudinal sectional view, partly inelevation, of an electric incandescent lamp according to the invention;Fig. 2 is an enlarged fragmentary perspective View of the mountstructure of the lamp shown Fig. i; Fig. 3 is an enlarged transversesection of the mount structure taken on the line 3--3 of Fig. 2; Fig. 4is a sectional view illustrating the method of forming the glass beadsand attaching them to the channel member of the mount structure; Fig. 5is a fragmentary perspective view of a modified form of mountconstructic-n according to the invention; Fig. 6 is a fragmentarysectional view on the line 66 of Fig. 5; and Figs. 7 and 8 are viewssimilar to Figs. 5 and 6, respectively, of another modification of theinvention.

Referring to the drawing, the lamp there shown is of the double-endedtubular type shown in the above-mentioned U. S. Patents 2,032,791 and2,158,849, and com prises an elongated sealed envelope 1 consisting of atubular glass bulb 2 having disc-shaped metal end caps or bases 3, 4fusion-sealed to its opposite ends to form end walls for the envelopeand contact terminals for the lamp. The said end caps or discs 3, 4 arepreferably made of a metal alloy which has a coefiicient of expansionapproximately the same as that of the glass of which the tube 2 is madeand which seals readily thereto by fusion. For a soft glass tube 2, theend caps 3, 4 are preferably made of a chrome-iron alloy containingabout 25-30% chromium. The end caps 3, d are preferably concave ordish-shaped so that they may be made of thin material while retainingadequate strength, and they are provided with centrally located bosses5, 6 which project axially inward of the envelope 1. The envelope 1 isexhausted through an aperture 7 at the center of the end cap 3, the saidaperture being sealed by a mass of glass 8 which constitutes thetipped-oh residue of a glass exhaust tube and which is sheltered withinthe cavity formed by the boss 5.

Mounted within and extending longitudinally of the envelope 1 is anelongated lamp mount 9 according to the invention comprising a filamentsupport structure 10 and an elongated filament 11 supported thereby. Thefilament support structure ltl comprises a stay member 12 composed of anelongated straight center section 13 extending longitudinally of thetube 2 adjacent the wall thereof and provided at its opposite ends withterminal wire or conductor extensions 14, 15. The center section 13 ofstay member 12 is preferably in the form of an approximately V-shapedchannel member to one end of which the terminal wire 14 is electricallyconnected as by welding. The other terminal wire 15 is insulativelysecured to the other end of the channel member 13 by a short length ofglass rod 16 in which the respective ends of the channel member 13 andwire 15 are embedded.

As shown, the terminal wires or end conductors 14, 15 extend from theopposite ends of the channel member 13 at a slight angle relativethereto, and their free or outer ends are bent to extend transversely ofthe channel member 13 and are formed into loops 17 which encircle thebosses 5, 6 on the respectively adjacent end caps to thereby positionthe lamp mount 9 within the envelope 1 with the filament 11 extendingmore or less axially of the said envelope. The loop 17 on one or bothterminal wires 14, 15 is initially formed with a slight pitch or spiralshape, i. e., it is formed as a coil of less than one full turn, for thepurpose of making the stay member 12 resiliently compressible to aslight extent longitudinally thereof. During the manufacture of thelamp, the spiral-shaped 3 loop or loops 17 more or less flatten out asthe stay member 12 is compressed between the opposite end caps 35, 4,the loops 17 thus resiliently bearing against the concave inner side ofthe end caps and so making good electrical contact therewith.

The filament 11 is in the form of a coiled tungsten wire which extendssubstantially the entire length and axially of the envelope 1 and isstretched out and clamped or otherwise electrically connected at itsends to short spur wires 18, 19 welded to the terminal wires l4, l5,respectively. The filament 11 is additionally supported ntermediatepoints along its length by one or more support or anchor wires 2%extending from the channel memher 13 at spaced points therealong, thesai support wires being provided at one end with filament-supportingloops 21 and being secured at their other ends and insulated from thechannel member by means of small glass support beads 22 in which thesupport wires 2% are embedded.

In accordance with the invention, the glass beads 22, in place of beingfastened to and held in place on the channel member 13 by means of afused glass-to-metal seal as has heretofore been the practice, aremechanically anchored to the channel member instead. For such purpose,the channel member 13 is formed, at spaced points along its lengthcorresponding to the location of the glass beads thereon, with lockingshoulders provided, in this instance by apertures 23 formed in thechannel member 13. The glass beads 22 engage and are immovably held inplace on the channel member 13 by the said locking shoulders, the glassbeads extending through and at least partially embedding the marginaledges of the apertures 23 so as to be locked to the channel memberwithin the said apertures. The attachment of the glass beads 22 to thechannel member 13 is performed by heating one end of a short length ofglass rod or a pressed powdered glass pellet 22' (Fig. 4) to a plasticcondition and then pressing the heated end down into the channel 13,which is also preferably heated to a slight degree, over the apertures23 therein so as to substantially fill the interior cross-sectionalspace of the channel at the respec tive apertures with glass and alsoforce some of the plastic glass down through the apertures and aroundthe outside edges thereof as shown at 24 in Figs. 2 and 3, thusembedding the marginal portions of the channel member bordering theapertures 23. At the same time some of the plastic glass is forced overthe upper edges 25 of the channel member 13 and around its outer sides,as indicatcd at 26, so as to also embed the upper edges of the channelmember in the glass of the bead. The result, therefore, is a secure andstrong clamping or mechanical interlock of the glass to the channel suchas effectively holds it immovably in place on the channel. .fter theattachment of the glass rods 22 to the channel member 13, the upper endsof the rods 22' are heated to a plastic condition and fused down,whereupon the support wires 2a are inserted endwise into and embedded inthe glass to complete the support wire mounting.

Inasmuch as the attachment of the glass beads 22 to the channel member13 is customarily effected by automatic means such as causes thelocation of the glass beads lengthwise of the channel member 13 to varywithin small limits, it is preferable that the apertures 23 be in theform of slots extending lengthwise of the channel memher so as to allowfor any such slight variation in bead location and assure that at leasta part of the glass forming the head will be forced through therespective apertures 23 and become locked therein. While, as shown, theapertures or slots 23 may be formed at the bottom of the V-shapedchannel member 13, they may, if desired, be formed in the sides of thechannel member instead.

in the modification of Figs. 5 and 6, the center stay section 27 isformed of a relatively rigid metal wire, e. g., nickel-plated iron wire,instead of metal channel as in the previous form of the invention. Thestay wire 27 is bent at spaced points along its length, corresponding tothe locations of the glass beads 23 thereon, into double or Sshapedloops 29 to form locking shoulders which are at least partially embeddedin the glass beads 23, as shown in Fig. 6, to thereby mechanically lockand hold the beads immovably in place on the stay wire 27. The glassbeads 28 may be attached to the stay wire 27 in the same manner manneras before, i. e., by heating one end of a short glass rod 22 to aplastic condition and pressing it down onto and at least part way aroundt.e underside of the looped Wire portions 29 so as to partly embed theindividual Wires forming the loop, as shown.

Figs. 7 and 8 illustrate another modification of the invention whereinthe center stay section 38 is composed of two side-by-side relativelyrigid wires 31 which are suitably secured together at points along theirlength, e. g., by spot-welrling or by twisting together, to form acomposite wire stay. At spaced points along their length correspondingto the locations of the glass beads 32 thereon, the two wires 51 formingthe composite stay wire 3% are bent oppositely away from each other orspread apart, as indicated at 33, to form apertures or longitudinalslots 34 in the stay wire which provide locking shoulders for the glassbeads 32. As shown in Fig. 8, the separated wire portions 33 of the staywire 3b are sulficiently embedded in the glass of the beads 32 tomechanically lock and hold the beads in place on the stay wire. Theapertures 34 are preferably elongated lon itudinally of the stay wire 3%in order to allow for slight variations in the longitudinal positioningof the beads 32 thereon during manufacture of the mount. In addition,the separated wire portions 33 of the stay wire are preferably eithercorrugated, crimped or otherwise suitably configurated, as shown, inorder to provide shoulders for locking the beads against longitudinalsliding movement on the stay wire within the slots 34. As in theprevious forms of the invention, the glass beads 32 are attached to thestay wire 39 by heating one end of a short glass rod 22 to a plasticcondition and then pressing it down onto the stay wire over the slots 34therein to force the glass through the slots and at least part way downaround the underside of the two separated wires 33 forming the slot, asshown in Fig. 8.

The mechanical fastening of the glass beads 22 to the channel member 13in accordance with the invention therefore permits the use of anordinary and much less expensive metal for the channel member other thanone, such as the high chrome-iron alloy heretofore employed for suchpurpose, which will seal to and wet the glass of the support beads.Thus, the channel member 13 may be formed of ordinary rolled iron orsteel, for instance, as a result of which the cost of the lamp mount andof the finished lamp is considerably reduced.

Although a pref-erred embodiment of my invention has been disclosed, itwill be apparent that the invention is not to be limited to the specificconstruction and arrangement of parts shown, but that they may be widelymodified within the spirit and scope of my invention as defined by theappended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An electric lamp comprising a glass envelope, a mount within saidenvelope comprising an elongated filament and an elongated metallic staymember extending longitudinally of the filament and carrying supportwires engaging and supporting the filament at spaced points ktherealong, said stay member being provided with apertures at spacedpoints therealong, and glass beads insulatively fastening said supportwires to said stay member, said stay member being of a metal other thanone which will wet the glass of said beads, and said glass beadsextending through said apertures and at least partially embedding themarginal portions of said stay member bordering the said apertures andmechanically locking the beads to the stay member within the saidapertures and holding them immovably in place thereon against movenientlongitudinally as well as laterally thereof, the said mechanical lockconstituting the sole means of attachment of the glass support beads tothe stay member.

2. An electric lamp comprising a glass envelope, a mount within saidenvelope comprising an elongated filament and an elongated metallic staymember extending longitudinally of the filament and carrying supportwires engaging and supporting the filament at spaced points therealong,said stay member comprising a metal channel provided at spaced pointstherealonc with longitudinally extending slots, and glass beadsinsulatively fastening said support wires to said channel, said channelbeing of a metal other than one which will wet the glass of said beads,and said glass beads extending through the said slots and at leastpartially embedding the marginal portions of said channel bordering thesaid slots and mechanically locking the beads to the channel within thesaid slots and holding them immovably in place thereon against movementlongitudinally as well as laterally thereof, the said mechanical lockconstituting the sole means of attachment of the glass support beads tothe stay memher.

3. An electric lamp comprising a glass envelope, a mount Within saidenvelope comprising an elongated filament and an elongated metallic staymember extending longitudinally of the filament and carrying supportwires engaging and supporting the filament at spaced points therealong,said stay member comprising an approximately V-shaped metal channelprovided at spaced points therealong with longitudinally extending slotslocated at the bottom of the channel, and glass beads insulativelyfastening said support Wires to said channel, said glass beadssubstantially filling the interior cross-sectional space of said channelat the region of respective ones of said slots and extending throughsaid slots and around onto the outer side of said channel and at leastpartially embedding the marginal portions of said channel bordering thesaid slots and mechanically locking the beads to the channel within thesaid slots and holding them immovably in place thereon against movementlongitudinally as Well as laterally thereof.

4. An electric lamp comprising a glass envelope, a mount within saidenvelope comprising an elongated filament and an elongated metallic staymember extending longitudinally of the filament and carrying supportWires engaging and supporting the filament at spaced points therealong,said stay member comprising a rigid wire having at spaced pointstherealong double loop-shaped bends lying in a common plane and definingapertures, and glass beads insulatively fastening said support Wires tosaid stay member, said stay member being of a metal other than one whichwill wet the glass of said beads, and said glass beads extending throughthe said apertures and at least partially embedding the marginalportions of said stay member bordering the said apertures andmechanically locking the beads to the stay member within the saidapertures and holding them immovably in place thereon against movementlongitudinally as Well as laterally thereof.

5. An electric lamp comprising a glass envelope, at mount within saidenvelope comprising an elongated fila ment and an elongated metallicstay member extending longitudinally of the filament and carryingsupport wires engaging and supporting the filament at spaced pointstherealong, said stay member comprising a pair of rigid Wires extendingalongside one another and securely fastened together at pointstherealong, said wires being locally bent oppositely away from eachother at spaced points therealong to conjointly form loop portions inthe stay member lying in a common plane and defining apertures in saidmember, and glass beads insulatively fastening said support wires tosaid stay member, said stay member being of a metal other than one whichwill wet the glass of said beads, and said glass beads extending throughthe said apertures and at least partially embedding the marginalportions of the stay member bordering the said apertures andmechanically locking the beads to the stay member within the saidapertures and holding them immovably in place thereon against movementlongitudinally as Well as laterally.

References tilted in the tile of this patent UNETED STATEs PATENTS1,607,515 Duncan Nov. 16, 1926 1,842,167 Hall Jan. 19, 1932 1,884,957Adams et al Oct. 25, 1932 2,032,791 Carton Mar. 3, 1936 2,082,616 CartonJune 1, 1937 2,425,864 Carton Aug. 19, 1947 2,425,865 Carton Aug. 19,1947 2,434,779 Willis Jan. 20, 1948

